Looking for Earthworms in Deadwood
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Looking for Earthworms in Deadwood
Ashwood, Frank, Vanguelova, Elena I., Benham, Sue and Butt, Kevin Richard
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Ashwood, Frank, Vanguelova, Elena I., Benham, Sue and Butt, Kevin Richard ORCID: 0000-0003-0886-7795 (2020) Looking for Earthworms in Deadwood. Frontiers for Young Minds, 8 . p. 547465. ISSN 2296-6846
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BIODIVERSITYPublished: 16 November 2020doi: 10.3389/frym.2020.547465
LOOKING FOR EARTHWORMS IN DEADWOOD
Frank Ashwood 1*, Elena I. Vanguelova 1, Sue Benham 1 and Kevin R. Butt 2
1Forest Research, Alice Holt Lodge, Farnham, United Kingdom
2Earthworm Research Group, University of Central Lancashire, Preston, United Kingdom
YOUNG REVIEWER:
MARIA
AGE: 14
Fallen branches, logs, and tree stumps are a valuable habitat in
forests, giving food and shelter to many organisms, including
earthworms. Unfortunately, deadwood is often removed from forests
because its value is not fully appreciated. We wanted to overcome
this by developing a sampling method for earthworms living in
deadwood in forests. By testing our new sampling method in oak
forests, we found that including deadwood in earthworm surveys
improves our knowledge of forest earthworm populations. We also
found a greater number of young earthworms in deadwood, where
conditions were warmer and moister than in the soil. By surveying
deadwood for invertebrates, such as earthworms, we can better
understand the important role that deadwood in forests plays in
maintaining biodiversity.
EARTHWORMS IN TREES?
Earthworms are important for maintaining healthy ecosystems: theirburrows help air and water enter soil, and they break down dead
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Ashwood et al. Looking for Earthworms in Deadwood
Figure 1
Figure 1
An epigeicearthworm found indeadwood. The paleband (or “saddle”)toward the head end(to the right) tells us thisis an adult earthworm.
plant material, recycling its nutrients back into the environment. Butearthworms do not just live in the ground, they can be found inall sorts of unexpected places—even up in trees and inside logs!Logs and fallen trees are called deadwood and are an important
DEADWOOD
In forests, woodymaterial that is nolonger living, includingfallen branches, logs,stumps, and standingdead trees. habitat for many di�erent types of earthworm, giving them shelter
and food (Figure 1). There are three main groups of earthworms:epigeic (living above-ground), endogeic (shallow-burrowing in soil),
EPIGEIC
Earthworms that live onthe surface of the soilin organic matter-richhabitats, like leaf litter.
ENDOGEIC
Earthworms that makeshallow, horizontalburrows, and feed onthe soil.
and anecic (deep-burrowing in soil) [1]. Earthworm populations in a
ANECIC
Earthworms that builddeep vertical burrowsand feed on organicmaterial on thesoil surface.
forest can a�ect how fast deadwood decays, with di�erent groups andspecies more important at di�erent stages [2]. This decaying wood is asource of nutrients and organic matter (organic compounds that are
ORGANIC MATTER
Matter composed oforganic compoundsthat have come fromthe remains oforganisms, such asplants and animals.
the remains of organisms, such as plants), and its decomposition isimportant for maintaining healthy forest soils.
DEADWOOD IS AN IMPORTANT BUT UNDER-STUDIED
HABITAT
Despite being a key source of soil organic matter and an importanthabitat, deadwood is often removed from forests when trees are cutdown for timber and firewood, putting many species of animals atrisk of going extinct [3]. Protecting forest biodiversity is important.
BIODIVERSITY
The variety of life in ahabitat, a high level ofwhich isusually desirable.
Biodiversity is the variety of life in a habitat, and we depend on theservices that healthy and highly biodiverse forests provide, such asstoring carbon and protecting soil. The more information we canlearn about the amount of biodiversity present in deadwood, thebetter we can understand the importance of keeping it in forests. Wedo not have a full idea of which earthworms live inside deadwood,because we do not currently have a scientific way of looking for themthere. Earthworm surveys normally only look in the soil and may missearthworms living in other places. By developing a way to surveydeadwood for earthworms, we can learn more about earthwormlifecycles and perhaps show how important it is to keep deadwood
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Ashwood et al. Looking for Earthworms in Deadwood
Figure 2
Figure 2
Earthworm sampling inan oak forest plot.Dashed white lineswithin deadwoodindicate sectionsdivided into separatepieces. All deadwoodwithin the plot and>10cm in diameter(dark gray) wasmeasured for totallength and midpointdiameter, and fiverandomly selectedpieces of mid- to latedecay were sampledfor earthworms. Alldeadwood <10cm indiameter or outside theplot was excluded fromthe survey (light gray).Five 0.1 m2 soil pits(indicated by crosses)were sampled forsoil-dwelling earthworms.
in forests. The main aim of our project was to develop and test amethod for surveying deadwood for earthworms. To test whether ourmethod worked, we compared our deadwood results with those froma standard soil-based earthworm survey.
SURVEYING DEADWOOD FOR EARTHWORMS
To try out our method, we visited 12 forests of common oak trees(Quercus robur) in Surrey, UK, and in each forest, we marked outa 10 × 10m square plot (Figure 2). In each plot, the total volumeof deadwood was recorded and we tried to determine which treespecies the deadwood belonged to. We also estimated how decayedthe deadwood was, based on a 1-to-5 ranking system, in which 1is least decayed (freshly fallen) and 5 is most decayed (deadwoodcompletely broken down into the soil). Since small branches havevery few earthworms in them, we selected five pieces of deadwoodthat were larger than 10 cm in diameter, and of mid- to late-decaystage (loose bark and wood beginning to soften). We analyzed thedeadwood by placing it onto a sheet and measuring its length anddiameter, so we could calculate its volume. Deadwood temperaturewas measured by inserting a digital kitchen thermometer beneathany loose bark. We then removed any moss and loose bark andinspected it for earthworms, and the remaining wood was taken apartand inspected. Once all earthworms were collected, the deadwoodwas then returned to its original location, with moss and loose barkreplaced as best possible.
SURVEYING SOIL FOR EARTHWORMS
We also sampled the soil for earthworms using a standard method.This involved digging soil pits (30 × 30cm wide and 10cm deep)
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Ashwood et al. Looking for Earthworms in Deadwood
Figure 3
Figure 3
Summary of the resultsfrom the earthwormsurveys of soil anddeadwood inoak forests.
at five locations in the plot (Figure 2). First, we placed the soil ontoa sheet to hand-sort for earthworms, and then we poured 5 L ofmustard water (25 g of table mustard powder mixed with 5 L ofwater) into each soil pit, to extract deep-burrowing earthworms,some of which can dig 2m deep! This mustard powder irritates theearthworms’ skin and encourages them to come up to the surface.Soil moisture and temperature measurements were also taken. Onceall earthworms were collected, the soil was placed back into the holes.All earthworms fromdeadwood and soil were preserved in alcohol andwere weighed, then each species was identified using a microscopeand an earthworm identification guide [4].
WHAT DID THE SURVEYS REVEAL?
Overall, we found a total of 1,012 earthworms and 13 di�erentearthworm species. The number of earthworm species was di�erentbetween soil and deadwood, with seven species found in deadwood,and twelve species found in soil (Figure 3). One species, Eisenia fetida,was found only within deadwood. This is an epigeic earthworm thatis often found in compost heaps. Six species were found only in thesoil: two epigeic, three endogeic, and one anecic species. All otherearthworm species were found in both deadwood and soil. Manymore juvenile (young) earthworms were found in deadwood thansoil, and deadwood was much moister than the soil and warmer byaround 1◦C.
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Ashwood et al. Looking for Earthworms in Deadwood
Total earthworm abundance (number of individuals) and biomassABUNDANCE
The number of aspecies or communityin an ecosystem, suchas the number ofindividuals per area.
BIOMASS
The mass of anorganism orcommunity oforganisms in an areaor ecosystem.
(mass of all earthworms) was much greater in soil than in deadwood(Figure 3). On average, the deadwood surveys contributed anadditional 81 earthworms and 209g earthworm biomass per 10 m2
forest plot.
THE BENEFITS OF DEADWOOD SURVEYS
By adding deadwood to our forest earthworm surveys, we found botha greater abundance of earthworms and more earthworm speciesthan we would have found by doing only soil surveys. There was amuch greater proportion of juvenile earthworms inside deadwood,where temperature and moisture conditions were more favorable.Earthworms are very sensitive to temperature and moisture extremes,so being protected in decaying wood allows earthworms to stay activethroughout the year, especially during summer drought and freezingwinter conditions. Removing deadwood from forests may thereforehave a negative e�ect on the many earthworm species that rely on itfor shelter and food. Based on our results, we can say that forest-basedearthworm research that does not include deadwood is likely tounderestimate earthwormpopulations, and forests without deadwoodwill have fewer earthworms. With more development, our surveymethod could be used for studying other important invertebratesthat live in deadwood, such as insects [3]. Hopefully we can use thisinformation to improve forest management practices, to make surethat deadwood is left in place to protect forest biodiversity.
ORIGINAL SOURCE ARTICLE
Ashwood, F., Vanguelova, E. I., Benham, S. and Butt, K. R. 2019.Developing a systematic sampling method for earthworms in andaround deadwood. For. Ecosyst. 6:33. doi: 10.1186/s40663-019-0193-z
REFERENCES
1. Hendrix, P. F. 1996. “Earthworms, biodiversity, and coarse woody debris in forest
ecosystems of the southeastern U.S.A,” in Proceedings of the Workshop on
Coarse Woody Debris in Southern Forests: E�ects on Biodiversity (Athens, GA).
p. 43–8.
2. Bouché, M. B. 1977. “Strategies lombriciennes,” in Organisms as Components of
Ecosystems, eds U. Lohm and T. Person (Stockholm: Ecological Bulletin).
p. 122–32.
3. Cálix, M., Alexander, K. N. A., Nieto, A., Dodelin, B., Soldati, F., Telnov, D., et al.
2018. European Red List of Saproxylic Beetles. Brussels: IUCN.
4. Sherlock, E. 2018. Key to the Earthworms of the UK and Ireland. 2nd Edn.
Telford: Field Studies Council.
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Ashwood et al. Looking for Earthworms in Deadwood
SUBMITTED: 31 March 2020; ACCEPTED: 20 October 2020;
PUBLISHED ONLINE: 16 November 2020.
EDITED BY: Malte Jochum, German Centre for Integrative Biodiversity Research
(iDiv), Germany
CITATION: Ashwood F, Vanguelova EI, Benham S and Butt KR (2020) Looking for
Earthworms in Deadwood. Front. Young Minds 8:547465. doi: 10.3389/frym.2020.
547465
CONFLICT OF INTEREST: The authors declare that the research was conducted in
the absence of any commercial or financial relationships that could be construed
as a potential conflict of interest.
COPYRIGHT © 2020 Ashwood, Vanguelova, Benham and Butt. This is an
open-access article distributed under the terms of the Creative Commons
Attribution License (CC BY). The use, distribution or reproduction in other forums
is permitted, provided the original author(s) and the copyright owner(s) are credited
and that the original publication in this journal is cited, in accordance with accepted
academic practice. No use, distribution or reproduction is permitted which does not
comply with these terms.
YOUNG REVIEWER
MARIA, AGE: 14
Hi, my name is Maria and I am from Poland. I absolutely love biology, especially
solving tasks in genetics and cell metabolism. In my spare time I enjoy reading books
and playing with my cat Roxi. I am keen on ballet. I train regularly at the Dance
Conservatory. I really love it!
AUTHORS
FRANK ASHWOOD
A passion for nature encouraged me to study Biology at university, where I
volunteered for research projects on invertebrate ecology in Scotland and Mexico.
After working as an environmental consultant for a few years, I went back to Uni and
did a Ph.D. studying earthworms on reclaimed landfill sites. I now have a great job as
a soil ecologist for Forest Research, where I study soil biodiversity in UK woodlands.
In my spare time I am a soil biology tutor and do macrophotography (taking photos
of the tiny animals living in soil). *[email protected]
ELENA I. VANGUELOVA
I have always been an outdoorsy person, spending lots of time in the mountains in
Bulgaria as a child. At University I studied Forest Engineering but was not entirely
happy until I did my Ph.D. in atmospheric pollution impacts on forest ecosystems.
Then I realized that what I really like is the environmental side of forestry and
soil. I work at Forest Research as a biogeochemist (a little bit of everything:
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Ashwood et al. Looking for Earthworms in Deadwood
biology, geology, and chemistry), and investigate the e�ects of a�orestation, forest
management, and environmental changes on forest soil biogeochemistry.
SUE BENHAM
I have always loved nature and spent my childhood climbing trees and watching the
natural world in the woods aroundmy home. Now I am a scientist at Forest Research
and I get paid to do the same thing! I spend my time working to understand how our
forests grow and what e�ect the changing climate is having on their condition. For
this I study all aspects of a tree’s environment, from the soil around its roots to the
air around its leaves and the animals that rely on it.
KEVIN R. BUTT
Kevin is an ecologist at the University of Central Lancashire. He has studied
earthworms for more than 30 years and is interested in how these ecosystem
engineers are able to assist humankind through their everyday activities, such as
burrowing and eating organic matter. He has studied earthworms throughout Britain
and undertaken research across Europe and in the USA. One of his current projects
is examining the action of earthworms on Charles Darwin’s estate, recreating
experiments of the great scientist, whilst another is investigating giant rainworms
in the mountains of Germany.
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